A photonic integrated device (also called a photonic integrated circuit (PIC)) combines optical or both optical and electronic components on a chip, in analogy to an electronic integrated circuit. A typical photonic integrated device carries and processes optical signals that travel in an array or network of waveguides, which can be optically coupled to optical fibers to carry the optical signal to and from the photonic integrated device.
Certain types of photonic integrated devices make use of planar lightwave circuits (PLCs) that support optical waveguides (“waveguides”) used to communicate light between the device components. A relatively high level of integration can be realized by forming the waveguides in a thin glass-based substrate. The efficient routing of the waveguide between device components requires that at least some of the waveguides include one or more bends. Unfortunately, such bends introduce loss of the optical signal power. Since there are other sources of optical signal loss (e.g., at optical interconnections, attenuation per distance traveled in the optical fibers and waveguides, etc.), it is important to reduce optical signal loss wherever possible to avoid having to amplify the optical signal or to increase detection sensitivity.